<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
  <style>
    .main {
      width: 400px;
      margin: 50px auto;
    }
    #canvas {
      width: 400px;
      height: 400px;
    }
  </style>
</head>
<body>
  <div class="main">
    <canvas id="canvas" width="400" height="400"></canvas>
  </div>
</body>
<script src="./js/scene.js"></script>
<script>
  let ctx = canvas.getContext('2d')
  let cx = 200, cy = 200
  let s = new Scene()
</script>
</html>